12.59 England has experimented with different 40-hour workweeks to maximize, production and minimize expenses. A factory tested a 5-day week

(8 hours per day), a 4-day week (10 hours per day), and a day week (12 hours per day), with the weekly production results shown in the c Is there evidence of a difference in the mean productivities for the three lengths of work-days?
d Form a 90% confidence interval for the mean weekly productivity when 12-hour workdays are used.